Surakarta— Santang mandarin orange peel (Citrus reticulata), which is commonly discarded as waste, has shown potential as a natural source of antioxidants. The finding comes from research by Ratna Sari Dewi and Tatiana Siska Wardani from the Pharmacy Program, Faculty of Health Sciences, Universitas Duta Bangsa, Surakarta, Indonesia. The study compared the antioxidant activity of three fractions of Santang mandarin orange peel—n-hexane, ethyl acetate, and water—using the DPPH method. The research was published in 2026 in the International Journal of Scientific Multidisciplinary Research (IJSMR).
The study found that all three fractions demonstrated free-radical-scavenging activity. The water fraction showed the strongest antioxidant activity, with an IC50 value of 73.464 ppm, followed by the ethyl acetate fraction at 75.705 ppm and the n-hexane fraction at 81.639 ppm. In the DPPH assay, a lower IC50 value generally indicates stronger antioxidant activity because a smaller concentration is required to inhibit approximately 50 percent of the target free radicals.
Santang mandarin is one of the local citrus varieties consumed in Indonesia. The fruit is commonly eaten fresh or processed into food and beverages, while the peel is often discarded. The article notes that the peel can account for around 40–50 percent of the fruit’s weight. Despite being treated as waste, the peel contains bioactive compounds, including flavonoids and phenolic compounds associated with antioxidant activity.
Antioxidants are important because the human body is continuously exposed to free radicals. These molecules are highly reactive and can interact with biological molecules. When free-radical production exceeds the body’s antioxidant defense capacity, oxidative damage may occur. Antioxidant compounds can help stabilize free radicals and reduce oxidative reactions.
The peel of Citrus reticulata contains several compounds that support its potential as an antioxidant source. Previous studies discussed in the article have identified compounds such as hesperidin, naringin, narirutin, flavonoids, and polyphenols. These findings provided the basis for Dewi and Wardani to further examine the antioxidant activity of Santang mandarin orange peel using different solvent fractions.
The researchers collected Santang mandarin orange samples from Sleman and Kulon Progo, Yogyakarta. A total of 20 kilograms of fresh fruit was used as the initial material. The peel was separated from the fruit, cleaned, dried, and processed into powder. After drying, approximately 8 kilograms of material remained, producing a 45 percent yield from the original wet weight.
The dried peel powder was then extracted using 96 percent ethanol through a maceration process. The material was soaked for 3 × 24 hours and the process was repeated until the filtrate became clear. The resulting extract was concentrated before being separated into fractions using solvents with different polarities: n-hexane, ethyl acetate, and water. This separation allowed the researchers to compare antioxidant activity among the different fractions.
Antioxidant activity was evaluated using the DPPH method. This method measures the ability of a substance to neutralize DPPH free radicals through a change in the solution’s color. The reaction can be measured using UV-Vis spectrophotometry. In this study, measurements were conducted at a maximum wavelength of 516 nanometers after a 30-minute reaction period.
Vitamin C was also used as a comparison. The vitamin C sample produced an IC50 value of 3.9986 ppm, considerably lower than the values recorded for all three Santang mandarin orange peel fractions. This indicates that, under the conditions of the experiment, vitamin C had stronger antioxidant activity than the tested orange peel fractions.
Among the three fractions, the water fraction recorded the lowest IC50 value. The n-hexane fraction had an IC50 of 81.639 ppm, the ethyl acetate fraction recorded 75.705 ppm, while the water fraction reached 73.464 ppm. The water fraction therefore demonstrated the strongest antioxidant activity among the three fractions tested.
Phytochemical screening also detected alkaloids, flavonoids, tannins, and saponins in the orange peel samples. Steroid and triterpenoid tests, meanwhile, produced negative results. The presence of several bioactive compounds provides a basis for further investigation of the antioxidant properties observed in Santang mandarin orange peel.
The findings could support efforts to make greater use of Santang mandarin orange peel, which is often discarded after the fruit is consumed. The material could potentially be explored as a natural ingredient for functional foods, nutraceuticals, and pharmaceutical research. However, the current findings are based on laboratory antioxidant testing and should not be interpreted as direct evidence that consuming Santang orange peel provides health benefits in humans.
Dewi and Wardani recommend further research to identify and characterize the specific bioactive compounds responsible for the antioxidant activity of each fraction. Future studies could also use advanced analytical techniques such as LC-MS and GC-MS, along with additional in vitro and in vivo tests, to provide a more comprehensive assessment of the potential of Santang mandarin orange peel as a natural antioxidant source.
Author Profiles
Ratna Sari Dewi — Pharmacy, Faculty of Health Sciences, Universitas Duta Bangsa, Surakarta, Indonesia.
Tatiana Siska Wardani — Pharmacy, Faculty of Health Sciences, Universitas Duta Bangsa, Surakarta, Indonesia.
Research Source
Article Title: Antioxidant Activity Test of N-Hexane, Ethyl Acetate, and Aqueous Fractions of Santang Mandarin Orange Peel (Citrus reticulata) Using the DPPH (1,1-Diphenyl-2-Picrylhydrazyl) Method
Journal: International Journal of Scientific Multidisciplinary Research (IJSMR), Vol. 4 No. 8, 2026, pp. 1693–1712.
DOI: https://doi.org/10.55927/ijsmr.v4i8.145
Journal Website: https://journalijsmr.my.id/index.php/ijsmr
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